Effects of rubidium on behavioral responses to methamphetamine and tetrabenazine.

Different groups of mice were injected subcutaneously every other day with rubidium chloride at three doses (0.41(50), 1.23(150) and 3.69(450) meq/kg (mg/kg)) or with saline as a control for a period of 2-3 weeks. Rubidium administered acutely did not affect spontaneous locomotor activities, while it tended to increase the activities when administered repeatedly though the increase was not statistically significant. The methamphetamine-induced hyperlocomotor activities were potentiated in the rubidium groups as compared with those in the saline group, this effect of ribidium being increased with prolongation of repeated administrations. Monotonic decreases in ambulation after tetrabenazine were not significantly affected in the rubidium-treated animals though the decreases were sometimes preceded by slight increases and recovery from the decrement tended to be more rapid. After tetrabenazine in the rubidium-treated groups, incidences of catalepsy were increased and jumping behavior and Straub tail responses occurred in a few cases. The results suggest that rubidium potentiates the excitatory action of methamphetamine on spontaneous locomotor activities, as contrasted with inhibitory influence of lithium.